There is a "request to delete" event you can sign and send to relays. Most of them will delete your post by now. So, if your keys leak, it doesn't matter if this service exists or now, they can just send a bunch of delete events, signed as you, while at the same time add new, fake ones, with whatever they want to scam your followers with.
Discussion
Yeah. Dangerous.
There could also be a “bad actor” relay though right? That doesn’t comply with delete requests and is just storing things for some potentially evil purpose?